Complete sewage treatment plant with submerged contact aerators



K. IMH FF Sept. 1, 1931.

COMPLETE SEWAGE TREATMENT PLANT WITH SUBMERGED CONTACT AERATORS Fild Nov. 9. 1927 mated Sept. 1, 1931 KARL 113031, ESE EN, Gm

COMPLETE SEWAGE TREATMENT PLAN! WITH seamen (XIITAGI AIR-ATOM Application fled. ll'ovembr a, 1921. Serial Io. aaaiea.

With the sewage treatment by submerged contact aerators it is advantageous to let the latter work in a separate tank and to effect the mechanical pre-settling as well as I the mechanical final settlingof the sewage in locally separate settling basins This 18 of particular importance for settling basins having scrapers for the removal of the sludge. The machines required for thls purpose can be worked in an easier way if the settling basins are quite independent of the contact aerators. I

The present invention relates to an improved sewage treatment plant embodying 15 this idea.

The accompanying drawings represent by way of example how the invention can be put into practice:

Figs. 1 and 2 are respectively a longitudinal section through part of, and a plan view of, the improved sewage treatment plant. I

The sewage flows, first, through a screen a, an oil catcher b, and a grit chamber a,

into the pre-settling basin d, then, into the tank e occupied by the submerged contact aerators, and, finally, into the final settling basin 9. Thepre-settling basin (2 and final settling basin 9 are fitted with the known Dorr scrapers, diagrammatically indicated by the broken diametric lines extending across the basins dand g, the sludge being thereby pushed to the middle and escaping with natural fall. From the pre-settling m. Hence, it is raised by the pump n into the separate sludge digestion chamber k. On its travel thereto, the sludge can be freed from the excess water in a separate chamber w, said water flowing through the overflow pipe 25 back into the settling basin (Z. From the sludge digestion chamber is the digested sludge is let-off through the pipe I on to the drying place 11?, Part thereof can, however, be returned through the pipe 1 to the pump shaft m, so that there it is mixed with the fresh sludge and thus by the pump n not only fresh sludge but a mixture of fresh and digested sludge is raised into the sludge digestion chamber. This is of importance for basin (Z the sludge flows into the pump shaft obviating the noxious acid fermentation. From the sludge digestion chamber 7: the

digestion gases are caught b means of a gas hood 2 and led through t e pipe 0 into the gas motor 12. 'Said motor drives the blower 9 wherein the compressed-air isproduced, which is led through the pi r to the submerged contact aerators in t e tank e. By means of the same' motor, also the osclllatlng motion of the air pipes below the contact aerators in the tank 0 can be produced. The gas motor is cooled by water froman ordinary water supply, the hot coolmg water being led throu h the pipe 8 into the bottom end of the igestion chamber whereby the latter is heated. The overflow water flows through the pipe t back to thereby less unnecessary sludge water is i brought into the sludge digestion chamber is, because the biological sludge from the final settling basin 9 loses a great portion of the sludge water during its simultaneous treatment with the sludge in the pre-settling basin (Z.

If the purification of the sewage obtained in the contact aerator tank does not suflice, it is possible to further treat the sewage by adding to the plant a second contact aerator tank at and a second final settling basin '0. The sludge from thelatter is also pumped into the inflow of the sewage to the pre-settling basin (Z. If required, it is even possible to add further additional contact aerator tanks and final settling basins.

The precipitation of the light biological sludge in the final settling basins can be facilitated by adding to the sewage, for instance at k, a chemical precipitation agent.

What I claim, is:

1. In a sewage treatment plant, a presettling basin having an inflow and a separate final settling basin, a tank having submerged contact aerators, pipe connections between said basin and tank including a connection for delivering sludge from the presettli basin to the tank and a connection for de 'verin sludge fromthe tank to the final settling asin, a sludge digestion chamber and means for conductin sludge there- 10 to from the pro-settling bas1n,"and means for deliverin biological sludge from the final settling asin to the inflow of the presettling basin there to be mixed with the sludge of the re-settlin basin prior, to

delivery to the 'gestionc amber.

2. In a sewage treatment plant a presettling basin having an inflow" and a separate final setth'ngbasin, a'tank having submerged contact aerators, pipe connections between said basin and tank including a connection-for delivering sludge from the pro-settling basin to the tank and a connection for delivering sludge from the tank to the final settling basin, a sludge digestion chamber, means for conducting sludge from the pro-settling basin to the digestion chamber including amixing chamber, an eflluent connection for removing part of the sludge from the di estion chamber to the mixi chamber wIiere to mix digested sludge and fresh sludge before delivery to the di estion chamber, and means for delivering biological sludge from the final settling basin to the inflow of the pro-settling basinthere to mix with the sludge of the pre-settling basin prior to delivery to the mixin chamber. e

3. n a sewage treatmentplant, a pre settlingbasin having an inflow and a sepa rate final settling basin, for precipitating 'biological sludge a tank having submerged contact aerators, pipe connections between said basins and tank including a connection for delivering sludge from the prer'settling basin to the tank and a connectlon for delivering sludge from the tank to the final settlin basin, a connection for delivering biologlcal sludge to said inflow for producing a biological sludge mixture in the presettling basin, a sludge digestion chamber, means for conducting the biological sludge mixture from the pre-settling basin to "the digestion chamber including a mixing chamber and pump for pumping the mixed sludge to the digestion chamber and means for leading off the excess water from the mixed sludge prior to its supply to the digestion chamber.

o 4. In asewage treatment plant, a tank having submerged contact aerators, two settling basins consisting of a pro-settling basin connected with the tank to deliver sludge thereto and a final settling basin to receive 05 sludge from the tank, connections for pumping biologicalsludge from the final settling basin into the inflow of sew e to the presettling basin, to produce a bio ogical sludge mixture in the pre-settling basin, a sludge digestion chamber and means for heating the same, means for conducting the biological sludge mixture from the pre-settling basin to the digestion chamber including a mixing chamber and ump for pum ing the mixed sludge to the i estion cham r, and an eflluent connection or removing part of the sludge from the digestion chamber to the mixing chamber.

5. In a sewage treatment plant, a presettling basin receiving the sewage inflow, a

separate final settling basin, a separate tank having submerged contact aerators, pipe connections between said basins and tank, to pass sludge from the pro-settling basin to the tank and from the tank to the final settling basin, a sludge digestion chamber having associated therewlth an excess water chamber, a mixinguchamber receivin sludge from the pre-sett g basin, means or conducting mixed sludge from the mixing chamber to the excess water chamber for therein set my hand.

KARL IMHOFF.

asin to the inflow tothe pre- 

